Centrifugal electric switches



June 28, 1960 c. F. MAY

CENTRIFUGAL ELECTRIC swI'ncHss 3 Sheets-Sheet 1 Filed Oct. 10, 1958 3 E M $6M & m\ v/ WV Q & w

' Filed Oct. 10, 1958 June 28, 1960 c." F. MAY 2,943,166

CENTRIFUGAL ELECTRIC SWITCHES 3 Sheets-Sheet 2 June 28, 1960 c; F. MAY- 2,943,166

CENTRIFUGAL ELECTRIC SWITCHES Filed Oct. 10, 1958 5 Sheets-Shget 3 United States Patent ice CENTRIFUGAL ELECTRIC SWITCHES Clifford Frank May, Birmingham, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England Filed Oct. 10, 1958, Ser. No. 766,428 Claims priority, application Great Britain Oct. 23, 1957 2 Claims. (Cl. 200-80) This invention relates to electric switches of the kind in which a movable contact member is actuated by a force derived from the centrifugal action of one or more masses pivotally supported on a rotary member. Such switches are commonly known as centrifugal switches, and the object of the present invention is to provide a centrifugal switch in a simple form adapted to control two or more associated circuits successively at different speeds of the rotary member.

-A switch in accordance with the invention comprises the combination of a movable contact member provided with two or more resilient arms and adapted to cooperate successively with associated fixed contact pieces, a rotary spindle having its axis at right angles to the plane of the said movable contact member, a pair of centrifugal masses situated at opposite sides of the spindle and pivotally mounted on a carrier formed on or secured to the spindle, and a sleeve carried by and axially slidable on the spindle for transmitting movements from the centrifugal masses to the movable contact member.

In the accompanying drawings:

Fignire 1 is a sectional side elevation of a switch embodying the invention.

Figure 2 is a front view of the switch contact members, and Figure 3 is a front view of the centrifugal mech anism.

Figure 4 is a front view and Figure 5 an edge view of the movable contact members, and Figure 6 is a crosssection on the line 6-6 of Figure 4.

In the example illustrated by the drawings, a housing 10 of any convenient shape has one end closed by a cover 11 made from electrically insulating material. On the inner side of this cover are mounted the movable and fixed contact members of the switch. The movable member (which is illustrated separately by Figures 4-6) is made from a disc of resilient metal sheet shaped to form .a pair of oppositely disposed arcuate arms 12, 13 and a straight diametrical part 14 herein referred to as the bridge. The ends 15, 16 of the arcuate arms are secured to the said cover, their other ends being integral with the opposite ends of the bridge. Preferably the latter is stiffened by flanges 17 at its edges. Also the arcuate arm :13 is made narrower than the arm 12 so that it can yield more readily in response to the axial force exerted on the centre of the bridge as hereinafter described. At each end of the bridge may be provided a single contact piece for co-operating with an adjacent fixed contact piece, or (and as illustrated) a pair of contact pieces 18, 19 are secured to opposite sides of one end of the bridge piece, and another pair of contact pieces 20, 21 are secured to the opposite end of the bridge piece. The contact pieces 18, 20 respectively co-operate with the contact pieces 22, 23 carried by metal arms 24, 25 which extend through the movable member and are secured to the cover 11, the said arms serving as or being secured to circuit terminals on the cover. The contact pieces 19, 21 co-operate with fixed contact pieces 26, 27 secured to other terminals on the cover. In the housing 2,943,166 Patented June 28, 196C is supported a rotary spindle 28, having its axis at right angles to the plane of the movable contact member. The spindle is embraced by a annular seal 29 contained in a recess in the housing and endwise movement of the spindle is prevented by a disc 30 on the inner end of the spindle and a collar 31 on the outer end, which abut against supporting surfaces on the housing. On the spindle is also secured a carrier 32 for a pair of pivoted centrifugal masses 33 located at opposite sides of the spindle, and on the inner end of the spindle is supported an axially slidable sleeve 34 having thereon an annular ridge 35 which engages grooves in the centrifugal masses. Also on the spindle is supported a non-rotatable sleeve 36. At the inner end of the sleeve 36 is provided a pressure pad 36a made from nylon or other electrically insulating material. This pad is of rectangular form and lies between the flanges 17 of the bridge to hold the sleeve 36 against rotation. Also it has formed on it a short cylindrical projection 37 which enters the contiguous end of the sleeve.

If required the outer ends of the said base 11 may be enclosed by a cover 38 for protecting the circuit terminals.

The arrangement in the example illustrated is such that at a predetermined speed, the sleeve 34 is moved axially by the centrifugal masses for imparting movement through the bridge 14 to the weaker arm 13 of the movable contact member, thus causing the contact piece 18 to open the circuit associated with the fixed contact piece 22 and close the circuit associated with the contact piece 26. At a higher predetermined speed, a further movement of the sleeve by the centrifugal masses causes the stififer arcuate arm 12 of the movable contact member to open the circuit associated with the contact piece 23 and close the circuit associated with the contact piece 27. With fall of speed the control of the circuits is effected in the reverse order.

A switch as above described is applicable to a variety of uses, but more particularly it is required for controlling a plurality of electromagnetic relays for effecting automatic gear changes in a variable speed power transmission system on a road vehicle, or for controlling an over-drive or under-drive mechanism associated with a vehicle power transmission system.

The invention is not, however, restricted to the example above described, as by appropriate modification of the movable contact member, it may be adapted to control any other number of associated circuits.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

!l. A centrifugal electric switch comprising in combination a plurality of fixed contacts, a plurality of movable contacts arranged to co-operate respectively with said fixed contacts, a movable metal member of rectilinear form carrying said movable contacts at its opposite ends, a pair of oppositely disposed resilient arms of arcuate form integral with and extending from opposite sides of opposite ends of the rectilinear member, a fixed support to which the outer ends of said arms are secured so that the resiliency of said arms permits movements of said rectilinear member for actuating said moveable contacts, one of said arms being weaker than the other so that the corresponding end of said rectilinear member is more readily yieldable than the opposite end thereof to pressure exerted on said rectilinear member at a position intermediate its ends, and thereby enables said movable contacts to co-operate successively with the corresponding fixed contacts, a rotary spindle having its axis at right angles to said rectilinear member and at a position intermediate the ends of the latter, centrifugally movable masses carried by said spindle, and a sleeve slidably mounted on said spindle for transmitting movements from said masses to said rectilinear member.

1 2.. A centrifugal electric switch according to claim 1, and having a pair of flanges extending from opposite edges of said rectilinear member, and a pressure pad of rectangular form provided on the adjacent end of said sleeve, and situated between said flanges to hold said 5 sleeve against, rotation.

References Cited in the file of this patent UNITED STATES PATENTS 2,621,267 Cripe Dec. 9, 1952 2,757,551 Long Aug. 7, 1956 2,779,836

Williams Jan. 29, 1957 

